US 7275024 B2
The present invention automatically generates a dimensional model from an object model. The relationships in the object model are used to infer foreign key relationships in the dimensional model.
1. A computer implemented dimensional model generation system having a tangible component, comprising:
a dimensional model generation component comprising a map system generating a data set schema based on mapping information and a model construction system, coupled to the map system, constructing a dimensional model based on the data set schema, the dimensional model generation component configured to receive, as inputs;
object model description information describing a relationship between entities in an object model;
a user-defined focal point of analysis identifying information in the object model as a focal point in the dimensional model; and
the mapping information indicative of a mapping between entities in the object model and a persistent data store;
the dimensional model generator being configured to automatically generate the dimensional model based on the inputs.
2. The dimensional model generation system of
a map object generator generating map objects based on user-provided mapping information; and
a map walker traversing the map objects and creating the data set schema based on traversal of the map objects.
3. The dimensional model generation system of
4. The dimensional model generation system of
5. The dimensional model generation system of
6. The dimensional model generation system of
7. The dimensional model generation system of
8. The dimensional model generation system of
9. The dimensional model generation system of
a model generator generating the dimensional model from the data set schema.
10. The dimensional model generation system of
a model materializer supporting an interface which, when invoked, materializes a specified dimensional model.
11. The dimensional model generation system of
a mapper component configured to receive the mapping information and generate a serialized representation of the user provided mapping information; and
a map loader, coupled to the mapper, configured to generate the map objects based on the serialized representation of the mapping information.
12. The dimensional model generation system of
13. A method, implemented at least in part by a machine, of generating a dimensional model from an object model that is mapped to a persistent data store, comprising:
automatically generating the dimensional model based on inputs including object description information indicative of relationships among objects in the object model, user-defined focal point information indicative of focal points of analysis in the object description information that is indicative of the object model, and mapping information indicative of mappings between objects in the object model and the persistent data store.
14. The method of
receiving the inputs as computer readable inputs.
15. The method of
generating a data set schema based on the mapping information.
16. The method of
constructing the dimensional model based on the data set schema.
17. The method of
generating map objects based on the mapping information; and
traversing the map objects and creating the data set schema based on traversal of the map objects.
18. The method of
retrieving relational database tables, having columns, based on the mapping information.
19. The method of
generating table and column objects for tables and columns retrieved.
20. The method of
applying foreign key relationships to the table and column objects created based on the relationships described in the object model description information.
21. The method of
identifying entities marked as focal points based on the focal point identifier.
22. The method of
generating a named query by traversing the foreign key relationships for table objects corresponding to the identified entities.
23. A computer readable medium having stored thereon computer readable instructions which, when executed, cause a computer to perform steps of:
receiving, as computer readable inputs, object description information indicative of relationships among objects in the object model, focal point information indicative of user-defined focal points analysis in the object model, indicated by the object description information and mapping information indicative of mappings between objects in the object model and the persistent data store; and
automatically generating and outputting the dimensional model based on the inputs.
24. The computer readable medium of
generating a data set schema based on the mapping information; and
constructing the dimensional model based on the data set schema.
25. The computer readable medium of
generating map objects based on the mapping information by retrieving relational database tables, having columns, based on the mapping information, generating table and column objects for tables and columns retrieved and applying foreign key relationships to the table and column objects created based on the relationships described in the object model description information; and
traversing the foreign key relationships and creating the data set schema based on traversal of the map objects.
26. The computer readable medium of
identifying entities marked as focal points based on the focal point identifier; and
generating a named query by traversing the foreign key relationships for table objects corresponding to the identified entities.
The present invention deals with satisfying reporting requirements for accessing data in a system modeled by an object model. More specifically, the present invention relates to a system for facilitating the reporting of business data by inferring a dimensional model from an object model.
When designing software applications involving business transactions, application developers conventionally use a model driven architecture and focus on domain specific knowledge. The model driven architecture often includes business objects (or business entities) involved in the business transactions, such as business entities corresponding to customers, orders and products. These entities are modeled as objects following the paradigm of object orientation.
Each object encapsulates data and behavior of the business entity. For example, a Customer object contains data such as name, address and other personal information for a customer. The Customer object also contains programming code, for example, to create a new Customer, modify the data of an existing Customer and save the Customer to a database.
The object model also enables a description of relationships among the business entities modeled. For example, a number of Order objects can be associated with a Customer object representing the customer who makes those orders. This is known as an association relationship. Other types of relationships can also be described, such as compositions. An Order, for example, can be “composed of” a collection of OrderLines. These OrderLines do not exist independently of the Order they belong to. In this way, application developers convert the business logic associated with their applications to a set of models. Applications are built that implement this business logic, often using on-line transaction processing (OLTP).
Objects in an object model typically store their data in a relational database. To satisfy traditional reporting requirements, data is retrieved through the relational database using extraction, transformation and loading (ETL) processes. Data is retrieved, using these processes, into a staging area known as a data mart.
Currently, there is a knowledge gap between users who work on data marts and those who perform OLTP application development. Those who work on data marts do not normally have knowledge about how the object model is constructed. Therefore, when the data is retrieved through the ETL processes, the business logic (such as the relationships and classes, etc.) that was built into the object model is lost.
Traditionally, therefore, in order to facilitate user's reporting requirements, another model known as a dimensional model is built from the data in the data mart. The dimensional model includes a Fact table, that has measures, and associated tables, that are referred to as dimensions. Once the dimensional model is built, a user can specify a query against the dimensional model to obtain data in a somewhat logical fashion, even through the business logic built into the object model was lost.
This type of system, however, requires that a great deal of time be spent in reconstructing the business logic (or at least part of the business logic) to obtain the dimensional model. This can require companies that use such systems to maintain two groups of programmers, one to develop the business logic and implement it in an object model, and another to support the reporting structure required by the company. Of course, this duplication of personnel is both costly and inefficient.
The present invention automatically generates a dimensional model from an object model. The relationships in the object model are used to project foreign key relationships in the dimensional model.
In one embodiment, a user specifies focal points of analysis for reporting. The user also specifies the object model and mappings from the entities represented by the object model to a persistent data storage system, such as a relational database.
In another embodiment, a second object model is automatically generated from the dimensional model. This allows a user to generate desired reports using only object oriented expressions. The object oriented expressions are translated to dimensional model query expressions which are executed against the dimensional model.
Appendix A is an example of an XML focal point specification file.
Appendix B is an example of a mapping file.
Appendix C is an example of pseudo code illustrating the operation of the model services system.
Appendix D illustrates the interfaces supported by components of the model services system and the entity generator.
Various aspects of the present invention deal with a system for inferring a dimensional model from an object model to enable efficient reporting and analysis of data, and creating an object model from a dimensional model. However, prior to describing the present invention in greater detail, one embodiment of an illustrative environment in which the present invention can be used will be described.
The invention is operational with numerous other general purpose or special purpose computing system environments or configurations. Examples of well known computing systems, environments, and/or configurations that may be suitable for use with the invention include, but are not limited to, personal computers, server computers, hand-held or laptop devices, multiprocessor systems, microprocessor-based systems, set top boxes, programmable consumer electronics, network PCs, minicomputers, mainframe computers, distributed computing environments that include any of the above systems or devices, and the like.
The invention may be described in the general context of computer-executable instructions, such as program modules, being executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The invention may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote computer storage media including memory storage devices.
With reference to
Computer 110 typically includes a variety of computer readable media. Computer readable media can be any available media that can be accessed by computer 110 and includes both volatile and nonvolatile media, removable and non-removable media. By way of example, and not limitation, computer readable media may comprise computer storage media and communication media. Computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by computer 110. Communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media. The term “modulated data signal” means a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, and not limitation, communication media includes wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, RF, infrared and other wireless media. Combinations of any of the above should also be included within the scope of computer readable media.
The system memory 130 includes computer storage media in the form of volatile and/or nonvolatile memory such as read only memory (ROM) 131 and random access memory (RAM) 132. A basic input/output system 133 (BIOS), containing the basic routines that help to transfer information between elements within computer 110, such as during start-up, is typically stored in ROM 131. RAM 132 typically contains data and/or program modules that are immediately accessible to and/or presently being operated on by processing unit 120. By way of example, and not limitation,
The computer 110 may also include other removable/non-removable volatile/nonvolatile computer storage media. By way of example only,
The drives and their associated computer storage media discussed above and illustrated in
A user may enter commands and information into the computer 110 through input devices such as a keyboard 162, a microphone 163, and a pointing device 161, such as a mouse, trackball or touch pad. Other input devices (not shown) may include a joystick, game pad, satellite dish, scanner, or the like. These and other input devices are often connected to the processing unit 120 through a user input interface 160 that is coupled to the system bus, but may be connected by other interface and bus structures, such as a parallel port, game port or a universal serial bus (USB). A monitor 191 or other type of display device is also connected to the system bus 121 via an interface, such as a video interface 190. In addition to the monitor, computers may also include other peripheral output devices such as speakers 197 and printer 196, which may be connected through an output peripheral interface 195.
The computer 110 may operate in a networked environment using logical connections to one or more remote computers, such as a remote computer 180. The remote computer 180 may be a personal computer, a hand-held device, a server, a router, a network PC, a peer device or other common network node, and typically includes many or all of the elements described above relative to the computer 110. The logical connections depicted in
When used in a LAN networking environment, the computer 110 is connected to the LAN 171 through a network interface or adapter 170. When used in a WAN networking environment, the computer 110 typically includes a modem 172 or other means for establishing communications over the WAN 173, such as the Internet. The modem 172, which may be internal or external, may be connected to the system bus 121 via the user input interface 160, or other appropriate mechanism. In a networked environment, program modules depicted relative to the computer 110, or portions thereof, may be stored in the remote memory storage device. By way of example, and not limitation,
In prior systems, in order to support a desired reporting structure, data was first retrieved from a persistent data store (such as a relational database) 201 using extraction, transformation, and loading (ETL) processes and placed in a data mart 208 which acted as a staging area for the data prior to retrieving it.
Then, developers supporting the reporting structure for the user generated a dimensional model, such as model 210. The dimensional model typically includes a Fact table 212 which has measures noted therein. The Fact table 210 also has a plurality of dimensions illustrated as D1-D5 in
However, typically, the application developers that implement business logic through object models are different, and have a different knowledge base, than those who develop dimensional models. Therefore, a great deal of time and effort has traditionally been spent in reconstructing at least a part of the business logic implemented through object model 200 in obtaining a dimensional model 210 which can be used for reporting.
Another difficulty associated with some prior art techniques is that even to generate reports from dimensional model 210 required the report generator to be familiar with multi-dimensional expressions (MDX). MDX can be difficult to learn because it has a complex syntax, and it is different than the object oriented expressions required to create and interact with object model 200. Therefore, even after dimensional model 210 was constructed, generating reports has still required personnel with specialized knowledge, other than that used in object oriented programming.
Prior to describing the invention in greater detail, the concept of foreign key relationships will be discussed.
The Time table 226 includes a primary key referred to as TimeID in field 228. The primary key uniquely identifies a record in the Time table 226. Time table 226 also contains a number of additional fields related to time, such as day, week and month.
Customer table 230 also includes a primary key field that contains a primary key referred to as CustomerID 232. The primary key of the Customer table uniquely identifies a record in the Customer table. Of course, the Customer table also includes additional items associated with the customer, such as customer name.
Therefore, the primary key in a table is a unique identifier for the records in that table. However, the TimeID field 222 and CustomerID field 224 in Fact table 220 are identifiers which refer to other tables (in this case 226 and 230, respectively). Therefore, the keys contained in fields 222 and 224 in Fact table 220 are foreign keys. Some complexity arises with respect to foreign key relationships. For example, a table cannot be deleted if its primary key is a foreign key in another table, without dealing with the foreign key relationship. Otherwise, such a deletion breaks the integrity constraints typically imposed on such systems.
Focal points 252 represent certain data in the object model that is marked by the user as being a focal point of analysis. Focal points 252 can illustratively be specified in an XML specification file. One example of an XML specification file is shown in Appendix A hereto.
Object description 254 is an input which describes the object orientation relationships in a set of metadata corresponding to a set of objects. This can take the form of, for example, a UML class diagram. One example of a UML class diagram for a plurality of business entities (Customer, Order and OrderLine) is illustrated in
Persistent data store mappings 256 map the data referred to by the object model to the persistent data store, in one illustrative embodiment the relational database 201 shown in
Model services system 250 receives inputs 252, 254 and 256 and automatically generates a dimensional model 258 based on those inputs. In accordance with one embodiment of the present invention, dimensional model 258 is inferred from the inputs supplied by the user, and there is no requirement for a second set of developers to be involved in recreating the business logic to obtain model 258. In one embodiment, and as will be discussed in greater detail below, model services system 250 uses the associations and compositions in the object model specified by the object model description 254 to infer foreign key relationships in dimensional model 258. System 250 also uses the focal points of analysis defined by the user in file 252 and the persistent data store mappings 256 to create dimensional model 258 and access data through model 258. Therefore, one aspect of the invention is simply the automatic generation of dimensional model 258.
However, even a system which automatically generates dimensional model 258 can be improved. For example, obtaining information through dimensional model 258 still requires the user to know MDX or some sort of dimensional model querying language. Therefore, in accordance with another embodiment of the present invention, entity generator 260 is provided. Entity generator 260 creates business intelligence entities 262 in the form of objects, from the cubes and dimensions in dimensional model 258. This is also described in greater detail below.
By looking at the entities and their relationships in object model description 254, it can be seen that the dimensional model will require a snowflake-schema, such as that shown in dimensional model representation 258. It can thus be inferred that two dimensions will be created, Order and Customer. The Order dimension will have two levels, Order and OrderLine. The measures (or numeric values) in the Fact table 266 will include UnitPrice and Quantity and will come from the OrderLine entities.
Model services component 300 provides a main user interface to accept focal point specification 252, object description 254 and ER mappings 256. Model services component 300 can also invoke the functionality associated with map system 302, dimensional model construction system 304 and entity generator 260. Thus, as a first step in the conversion process, model services system 250 receives, through the top level interface implemented by component 300, focal point specification 252, object description 254 and persistent data storage mappings 256. This is indicated by block 320 in
For the sake of the present example, a more detailed object description than that shown in
Model services component 300 provides these inputs to map system 302 and invokes certain functionality in map system 302. Using the ER mapper, the user produces serialized ER maps 256 to described how the object model is mapped to the relational database. These serialized maps 322 are then loaded by map loader 308. Map loader 308 deserializes those maps and converts them to entity map (EM) objects 324. The precise form of EM objects 324 is not important. They are simply objects generated from the serialized maps 322 that are predefined such that the structure of EM objects 324 is known by map walker 310. Loading maps 322 and creating EM objects 324 is indicated by block 323 in
Map walker 310 navigates EM objects 324 and generates a data set schema to represent tables and columns that the entities are mapped to in the relational database, and to represent the relationship among them. Navigating the EM objects to create data set schema 326 is indicated by block 325 in
Model materializer 314 provides an interface to materialize the dimensional models generated by model generator 312. Materializing the dimensional models is indicated by block 332 in
Foreign key relationships among the table and column objects created are projected based on the associations and compositions among objects described in the object model description (such as the UML class diagram) being processed. The map walker 310 then traverses foreign key relationships from each table object created, for a corresponding entity that has been marked as a focal point for analysis. Recall that the focal points are specified by a focal point specification file which has also been input by the user. The foreign key relationships are traversed in a many-to-one direction toward table objects whose corresponding entity has been marked as a focal point for analysis, in order to generate a named query. The named query can be synthesized by combining the identified tables using an appropriate persistent data store query statement (such as a structured query language (SQL) statement). Thus, the named query is designed to reach out to other dimensions associated with each table object, based on focal points specified by the user.
The named queries are then used to create logical view objects for the dimensional model. This is indicated by block 408. A dimensional model cube is then built for each logical table object, with other table objects linked to it as dimensions. This is indicated by block 410.
Appendix C illustrates another embodiment of pseudo code illustrating how model services system 250 calls the various components thereof in order to implement the functionalities discussed.
It should be noted, at this point, that the dimensional model, an example of which is shown in
An exemplary query for querying the dimensional model illustrated by
As also indicated above, MDX and other dimensional model querying languages can have fairly complex syntax or be otherwise difficult to learn. Therefore, another embodiment of the present invention converts the automatically created dimensional model into another set of objects referred to herein as BI entities 262 so that they can be queried by users using object oriented expressions, rather than the complicated syntactical expressions required by dimensional model querying languages. To satisfy the reporting requirements of the client it is not enough to query the original object model, because the dimensional model may have a Fact table which has attributes from two different entities in the object model as dimensions thereof. Therefore, in order to make it easier to access the dimensional model, in accordance with one embodiment of the present invention, BI entities 262 are created.
BI entities 262 provide a conventional object oriented view of the underlying dimensional model 258. A user can thus create efficient query criteria and consume dimensional data in a manner in which the actual querying of the dimensional model is performed transparently to the user. BI entities 262 hide the dimensional model details, such as the cube, the dimensions, the hierarchy, the native query language, etc., and the user is only required to use objects and attributes.
In order to generate BI entities 262, recall that entity generator 260 has access to underlying dimensional model 258. Entity generator 260 first retrieves a Fact table from dimensional model 258. This is indicated by block 510 in
Entity generator 260 then generates a non-primary BI entity for each dimension of the Fact table. It should be noted that nested classes can be used to maintain the original structure, hierarchy, and levels of the dimensional model. Generating the non-primary BI entities is indicated by block 514 in
The user input query 520, input through BI criteria 504, is converted by BI service component 502 into a dimensional model query expression, such as an MDX expression, which can be executed against the dimensional model 258. One exemplary class diagram for BI service component 502 is illustrated in
MDX set functions supported:
Cross join, children, descendants, ancestors, all members, members, etc.;
MDX member functions supported:
CurrentMember, DefaultMember, FirstChild, LastChild, Lead, Lag, etc . . . ;
MDX numeric functions supported:
Average, Aggregate, count, sum, max, min, median, IIF, etc . . . .
Table 1 lists one exemplary set of MDX operators which are supported.
The following illustrates one exemplary criteria definition which forms the user input query 520 in the C-Sharp programming language.
After the dimensional model query is executed, BI service component 502 then returns a result set as indicated by block 528 in
Finally, BI metadata discovery component 506 can also be provided. BI metadata discovery component 506 is illustratively provided to perform a system wide BI entity search and to return detailed metadata retrieved for one or more BI entities. Of course, this can be useful to the user.
An example of how data is accessed may be helpful. By way of example, assume that a Sales cube in dimensional model 258 has two measures, SalesUnits and SalesDollars, and one dimension “product” which in turn has only one hierarchy “cat”, which in turn, has one level “category”. The generated BI class codes illustratively looks as follows:
One example of a user input query input through BI criteria component 504 is as follows:
An illustrative and exemplary result set returned based on the user input query is shown in
It can thus be seen that the present invention provides a number of significant advantages over prior systems. One aspect of the present invention automatically generates a dimensional model from an object model. The automatic generation is performed by inferring the dimensional model from relationships specified in the object model and user-designated focal points, as well as mappings back to the relational database.
In another embodiment of the present invention, objects are provided to abstract away from the specifics of a dimensional model. Therefore, a user can access a dimensional model using only object oriented expressions, without requiring specific knowledge of any dimensional model querying language.
Of course, in another embodiment of the present invention, both systems are used together such that the dimensional model is automatically created from a user-specified object model, and the entities which abstract away from the dimensional models are automatically created as well. Thus, all a user must do is provide the focal points, a description of the object model and its persistent data storage mappings, and this embodiment of the present invention automatically generates the necessary components for the user to access the data according to a desired reporting structure using only object oriented expressions without going through the laborious tasks of manually creating a dimensional model and then generating dimensional model-specific queries against the dimensional model.
Although the present invention has been described with reference to particular embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.